Background: Long-lasting pain and disability, known as chronic whiplash-associated disorder (WAD), may develop after forced flexion-extension trauma to the cervical spine. Mechanisms behind WAD are virtually unknown, as are the possible effects of early intervention. This trial was undertaken to compare the effect of three early intervention strategies for the prevention of developing chronic WAD following acute whiplash injury.

Methods: 458 participants were randomised to one of 1) stiff neck collar, 2) advice to act-as-usual, or 3) an active mobilisation regime. Participants were followed for one year and treatment effects were compared in terms of lasting neck pain, headache, disability and sick-leave.

Inclusion Criteria:

• Been exposed to rear-end or frontal car collision
• Experienced symptoms within 72 hours
• 18 - 70 years

Exclusion Criteria:

• Could not be enrolled within 10 days of the collision
• Fractures or dislocations of the cervical spine
• Amnesia for the accident
• Unconsciousness in relation to the accident
• Injuries other than the whiplash injury
• Average neck pain during the preceding 6 months exceeding 2 on a box scale 0-10, where 0= no pain and 10= worst possible pain
• Significant pre-existing somatic or psychiatric disease
• Alcohol or drug abuse
• Does not read or understand Danish.